Engine speed governor



Sept. 18, 1951 D. BOH N 2,568,380

ENGINE SPEED GOVERNOR Filed Aug. 23, 1945 2 Sheets-Sheet 1 y 3 a I 3 II. w F o w B 2 7 m 6 f o w m 9 1!! w R m R F a" 0 m it; h F V A w H W H 3 P 8 1 INVENTOR. DON/4L0 BOH/V BY Q MMC v :QTTORNGYS TI'I'IIIIIH FIG. 2

Sept. 18, 1951 1, BOHN 2,568,380

ENGINE SPEED GOVERNOR Filed Aug. 23, 1945 2 Sheets-Sheet 2 FIG.6

4 INVENTOR. DONALD BOH/V ATTORNEY S Patented Sept. 18, 1951 UNITED STATES PATENT OFFICE ENGINE SPEED GOVERNOR Donald I. Bohn, Pittsburgh, Pa. Application August 23, 1945, Serial No. 612,243

13 Claims. 1

In the control of engines, it is often desired to have a device which will maintain the speed constant under varied conditions of load. Such, for instance, would be the case in an enginedriven generator where it would be desired to hold a constant voltag and hence speed independently of the degree of electrical loading.

Such devices, called governors, become more complicated if it is also desired to vary the speed manually from time to time. Such might be the case, for instance, in an automobile wherein a speed would be chosen by th operator by setting a hand or foot lever and wherein variations of load would arise from changes in the grade of the highway.

It is known, for instance, that under a fixed throttle opening an automobile would tend to slow down on up-grades and speed up on downgrades. With a proper adjustable governor this could be prevented while at the same time maintaining manual control of the speed at the discretion of the operator.

It is one of the objects of this invention to provide means for accomplishing this purpose in a simple and novel way.

This invention makes use of the centrifugal governor of the liquid type. It is well known that a rotating liquid assumes a curved surface, low in the center and higher toward the periphery. In this invention a rotating mercury pool having this property replaces in a sense the rotating balls of the classical steam engine governor. The depression of the center of a rotating mercury pool is used in this invention to vary the depth of immersion into the pool of a special graphitized electrode.

The resistance properties of this graphitized electrode when partially immersed in mercury play an essential role in the functioning of the device.

The operation of this governor in the first simple condition of a fixed speed adjustment can be described as follows: A graphitized electrode such as described above is immersed in the center of a. mercury pool which rotates at or proportional to the speed of the prime mover, or engine. If now the engine speed should change, the depth of immersion of the graphitized electrode would change and hence the electrical resistance as measured betweent he electrode and the mercury pool would change.

In operation this electrical resistance is used to control the current in a torque motor which actuates the throttle of the engine. The torque motor and throttle are so arranged that an increasing current in the motor causes the throttle to open wider. If now the engine and associated governor had been operating at a stable equilibrium speed and if for some reason, for instance, by the application of an additional load the engine was momentarily slowed down, reducing the angular speed of the mercury pool, the level of the mercury at the center of the pool would rise thereby increasing the length of the graphitized electrode immersed and hence reducing the electrical resistance between the electrode rnd the mercury.

This would in turn increase the electrical current in the torque motor and thereby increase the throttle opening tending to accelerate the engine and thereby return it toward the previous equilibrium speed. It is thus seen that such a mechanism has the characteristics of a governor, namely that it creates an action at the throttle which tends to oppose changes in speed imposed by external loads or their removal.

The rigidity with which the speed is maintained depends upon the amount of incremental rotation of the throttle resulting from a given incremental change in engine speed. This depends in turn upon the incremental rise in the mercury level at the center of the pool for a given incremental change in the engine speed, and further depends upon the change in resistance measured between the graphitized electrode and the mercury pool fora given ris in mercury level.

For the purposes of this invention, graphitized electrodes are to be used which produce large and rapid change i resistance with the degree of immersion. It has been, for instance, experimentally determined that the graphitized electrodes employed will change resistance between 5 and ohms for a change in immersion depth of something in the order of /8 of an inch.

By the proper design of a torque motor it is quite possible to cause the throttle to move from a completely closed to a completely open position by virtue of such a change in resistance interposed in series with the electrical circuit t the torque motor. It is hence seen that this device is capable of operating as a quite rigid governor holding engine speeds within their limits.

The above description contemplated only the single fixed speed. If now it is desired to change the regulated speed manually, this can be accomplished by various means which are to be described in more detail below. One such means would be to control manually the vertical position of the grap-hitized electrode. A second such means would be to change th quantity of mercury in the rotating pool. This could be virtually accomplished, for instance, by changing'the degree of immersion into the pool of auxiliary solid objects. Such a manual adjustment could also In this arrangement the ratio of the variable speed transmission is manually adjusted but no adjustments on the governor itself are made.

Hence the governor always operates at a fixed speed regardless of manual adjustment while the engine speed may be chosen at will.

It is a further purpose of this invention to provide a novel construction of this variable speed transmission which overcomes many of the difiiculties inherent in conventional types. Conventional continuously variable transmissions often require considerable force in their operation and can usually not be adjusted to a predetermined position when the engine is not rotated. The continuously variable transmission to be described below overcomes these difliculties.

In the above description mention has been made of a mercury pool rotating at the engine speed or at a speed proportional thereto. It is quite obvious that-a simple open mercury pool contained in a vessel would rotate at the same speed as the vessel if time were allowed for the liquid to accelerate or decelerate to its equilibrium speed; but it is also clear from common experience that some considerable time would usually be required for this equilibrium to be attained. It is therefore quite advantageous to use a modified form of mercury pool whereby the rotation of the fluid is almost instantaneously determined by the speed of rotationof the vessel.

This and other details will become clearer from the following description and drawings in which Figure 1 is a schematic diagram of the mechanism of the governor.

Figure 2 is a detailed design of the rotating mercury vessel and associated graphitized electrode with means for manually adjusting the height of the electrode.

Figure 3 is a less elaborate version of a rotating vessel whereby manual adjustment of the speed is accomplished by varying the immersion of a non-rotating cylindrical member.

Figure 4 is a complete diagram of a practical embodiment of the invention including a novel variable speed transmission.

Figure 5 is a cross-sectional view on line 5-! of Figure 4.

Figure 6 is a side view of the means for shifting idler 36 of Figure 4.

In Figure 1 is shown a schematic diagram of my novel device without specificmeans for a manual adjustment of the speed. The device consists of two main assemblies, one of these being the rotary solenoid which operates the butterfiy valve controlling the mixture of gas to the engine. This solenoid is shown as assembly A. It consists primarily of a field frame I with windings disposed as shown on its two poles, this being similar to the construction used on an ordinary two pole D. 0. motor. The rotor 2 which is a solid block of iron is machined with a full radius or raised portion 2a represented in the left-hand sketch entitled Face of Rotor."

A depressed portion 2b is adjacent to this V-shaped raised portion 2a. This is to give the rotor the effect of decreasing reluctance with increased iron area adjacent to the field poles as the rotor is moved counterclockwise from its normally de-energized vertical position. This. combined with a torsion spring 3 as shown, will give an approximate straight-line characteristic between current in the rotor and angular position in a counterclockwise direction. This rotor could be on the same shaft with a conventional butterfly valve 20 regulating the gas supply to an engine as is now done with the foot throttle of an automobile. Alternatively a steam throttle or any other prime controlling lever of an engine could be connected to the shaft of the torque motor.

Speaking in terms of an automobile engine for convenience, therefore, one result of the assembly A, regardless of the controlling means employed, is that the butterfly gas valve may be .smoothly opened or closed over its full range when the immersed graphitized electrode member 6 has its immersion varied a small amount, such as /sff o r into mercury pool 5. In an automobile, assembly A would be operated from the car supply of 6 volts, D. C., but obviously for other applications any desired D. C. voltage may be employed.

The operation of the device is now clearly evident from the schematic diagram of Figure 1. Electric current flows from the battery supply through the mercury pool 5, graphitized electrode 6, and its metal holder 4, through the winding around the core I of the torque motor back to the battery. If any external influence should slow the speed of rotation of the mercury pool, the level of the mercury 5 would rise thereby decreasing the resistance of the graphitized electrode 6 resulting in the increase in current in the torque motor causing the butterfly valve to open and hence check the fall in speed.

If on the other hand the speed should tend to rise, precisely the opposite phenomenon would occur.

In Figure 2, a detailed design of a rotating mercury pool with associated electrode and means for manually controlling the height of the electrode is shown. In Figure 2, assembly B consists of a steel block 1, which may be rectangular or circular or of any other; but which is cross-section turned cylindrical at its upper and lower portions as shown. This block I is drilled with two slanting holes 8, one on each side, and also with a double diameter hole 9 down the center of the block. Holes 8 are connected at their top and bottom with hole 9 by means of small horizontal holes l0 and II. Suitable plugs l2, l3 and M are provided. to seal up these holes from the outside.

Extending downward in the upper hole 9 is an insulating bushing 15 which acts both as an insulator and a guide for;.metal stem I6 which carries at its lower end graphitized immersion member 6. A compression spring I1 is provided to maintain stem IS in a' normal upward position. Lever l8 performs two functions, it being used to cause a vertical motion of plunger i! from the operation of the foot throttle or manual control and in addition it forms a contact means with the graphitized immersion member 6 to the external circuit 'as indicated in Figure 1.

The lower portion of assembly B is turned into a shaft l9 carried on suitable bearings and driven directly from the engine to be controlled at a suitable speed ratio.

With the device stationary and prior to assembly, a certain amount of mercury is placed inside. giving a normal level as indicated by dotted line 20. Under this condition the graphitized immersion member 6 just barely dips into the mercury in tube 9. Also, under this condition the current in the control circuit is so low that the armature on the rotary solenoid shown in assembly A is in its neutral position, this normally being adjusted so that the butterfly gas valve is at idling speed.

If the operator by means of the foot throttle actuates lever "3 so as to depress rod l1, the lowered resistance between graphitized immersion member 6 and the mercury will be reduced to a value depending upon the motion of lever l8. If this reduction in resistance is sufflclent to cause butterfly gas valve to open half-way, the engine will then speed up due to the additional gas supply and in so doing rotation of block I will, owing to centrifugal force, lower the mercury column in hole 9 tending to raise again the resistance between the graphitized immersion member 6 "nd the center mercury column; the mercury in column I will rise correspondingly. Quite obviously a balance will be obtained and the engine will operate at this newly adjusted speed. Since the entire system of holes 8, 9, l and II are interconnected, air displaced by raising columns 8 will flow through openings ll into the top of column 9 so that no excess air pressure will impede accurate relative movements of the mercury columns. The lower openings In permit column 9 to drop and columns 8 to rise under the influence of centrifugal force.

Assume now that lever I8 is left in its last position and that a load is placed on the engine. This will, of course, slow the engine down, causing the center mercury column to rise and opening the butterfly gas valve sufliciently to maintain substantially the engine speed which existed under no-load conditions. The change in depth of immersion of graphitized immersion member 6 required to cause butterfly gas valve to operate over its entire range determines the speed regulation of the governor under any fixed position of lever i8. Since the characteristics of the graphitized electrodes cause a very large change in resistance on a small change in degree of immersion, this regulation of speed will be quite rigid.

By confining the mercury to the holes 8 which are located off the center of rotation, it is possible to force the mercury to respond quickly to changes in speed of the vessel and not to spin relative to'the vessel.

In Figure 3 is shown an assembly C which operates on the same general principles as assembly B. However, in this case the mercury is not confined as previously and hence would not respond as quickly to changes in engine speed. Other differences are that in design of assembly 0 a metal rod 2| which carries the graphitized immersion member 6 is fixed and is not used as a control member.

The assembly consists of a metal cup 22 which is made into a shaft at its lower portion, supported in bearings and driven by the engine. A metal sleeve 23 which does not rotate is carried on a forked member 24 which is operated by the foot throttle so as to move sleeve 23 up or down. Assume that metal sleeve 23 is in its maximum upward position. this being with the foot throttle in its normally closed position; with the mercury level somewhat as shown, if the engine has started, it will go to a certain idling speed controlled by the depth of immersion of graphitized immersion member 6 in the mercury. This condition is indicated by the dotted line showing the level of the mercury at idling speed.

If now, the operator depressed the foot throttle, sleeve 23 will be lowered, the extent of such lowering determining the effective slowing up of the mercury rotation in the center of the cup. This will raise the mercury level, increasing the immersion of graphitized immersion member 6, tending to open the butterfly gas valve. The engine will therefore speed up until equilibrium is reached. It will thus be seen that a given engine speed within reasonable limits will exist for each vertical position of sleeve 23 regardless of the load on the engine.

In Figures 2 and 3, assemblies B and C represent two designs, both of which require that the mercury and its graphitized immersion member 6 be exposed to air.

Both assemblies B and C can be modified to permit hermetic sealing and if this is done an inert gas, such as hydrogen, may be used to prevent any possibility of oxidation. Such hermetic sealing in the case of assembly B, Figure 2 may involve some form of bellows connecting the upper portion of stem [6 with the upper portion of block 1 or its turned end through suitable electrical insulation. The entire device C might be hermetically sealed with sleeve 23 controlled vertically and restrained from rotating by means. of a magnet outside of the rotating cell or a similar bellows arrangement may be used over the. top of sleeve 23 and between sleeve 23 and cup 22..

A third variation of the invention utilizing the. variable speed transmission mentioned previously makes the problem of hermetically sealing even. simpler since there would be no moving parts at. all in the rotating vessel except for the fluid. mercury.

This modification is shown in detail in Figures. 4 and 6 in which the steel angle 3| forms the base.- of that part of the mechanism which is driven. by the engine. In this particular design which may, of course, vary greatly in its application, steel angle 3| is to be mounted alongside of the automobile engine head so that metal wheel 32 contacts the fan belt and is driven by it at a fixed ratio to engine speed. Metal wheel 32 is mounted on shaft 33 which rides in bearings 34. Driving wheel 35 which is machined with a spherically concave surface as shown, is contacted at any portion of its spherical driving surface by the fiber disk idler 3B which is mounted on a metal wheel 31 which carries ball bearing 38 at its center. A shaft 39 goes through the ball bearing and is provided with spring saddles in its extremities. Shaft 39 also goes through forked member 43 which carries the idler disk assembly.

Driven wheel 4| which is made similar to wheel. 35 except with somewhat different proportions, is rigidly fastened to vertical shaft 42 which ridesin bushings 43.

The mechanism of Figure 4 described so far comprises the variable speed transmission which drives vertical shaft 42 which is made integral with the lower part of the centrifugal mercury governor 44.

It will be clear that in the position shown for idler 36, shaft 42 is driven at the slowest speed. As disk 36 is rotated angularly to the dotted line aoaaseo 7 position, shaft 42 is driven at the highest speed. Various intermediate positions of disc 36 result in various intermediate speeds of shaft 42.

Centrifugal governor 44 is made of two steel members, a lower part 45 which may be integral with shaft 42 and an upper part 46. Part 46 has four blind, equally spaced, vertical holes 41 and a central hole 48. Four small connecting holes 49 form a passage between holes 41 and central hole 48.

Part 46 rests on and is welded to part 45 which is also provided with a central hole 50. In addition, four smaller holes are drilled at an angle as shown to provide connecting passages from the lower portion of hole 50 to the four blind holes 41.

An insulating bushing 52 threads into part 46 as shown and-carries in its axis a metal rod which connects at its top toa metal cap 53 and at its bottom end with a special pointed graphite member 54. This latter assembly, running from the cap 53 to the metal graphite 54, is insulated from the outer portion of bushing 52 in a manner similar to that done with a spark plug; hence hermetical sealing is relatively easy.

A second part of this modification of the invention, not mechanically connected to the above described assembly, consists of an electrically operated butterfly valve 55. Mechanically, this butterfly valve is about the same as is employed in an automobile carbureter but, instead of bein operated directly from the foot throttle, it is operated by an electrical torque motor 56. This torque motor consists of a steel armature 51 made somewhat as shown in section in Figure 4 and having an end view as shown in the section of Figure 5. The stationary magnetic members 58 form a portion of the magnetic circuit represented by cores 59, iron member 60, and steel armature 51. A torsion spring 6| is mounted at the other end of the shaft of the butterfly valve and is so disposed that when torque motor 56 is de-energized, torsion spring 6| will move the butterfly valve to its closed position.

The design characteristics of torque motor 56, coordinated with torque spring 6|, are such that when a certain low value of current flows in the coils 62, the butterfly valve will start to open and as this current is increased incrementally, the valve will take a new and more open position for each stop of increased current.

The proper desired operation of the various parts is based upon a coordinated design between torque motor 56, torsion spring 6|, and the characteristics of pointed graphite resistor 54, and this coordinated action will now be explained.

The electrical circuit consists of a ground connection 63 connected to one terminal car battery 64 through coils 62 to a contacting member 65 and when mercury in governor proper 44 is contacting pointed graphite resistor 54, the circuit is completed through the mercury and back to ground.

Initially, a certain amount of mercury is poured into governor 44 through the central hole 48 and since all of the various passages are connected together, it will assume, when the device is at rest, a predetermined level A in both the outer slanting holes 5| and the central hole 50. When bushing assembly 52 is installed as shown and an electrical connection is made to its cap by means of spring 65, the electrical circuit will be completed and, since the pointed graphite resistor 54 is completely immersed in mercury (since it is below the predetermined level A) the butter- 8 fly valve 55 will be closed, as previously described.

If now governor 44 is rotated, the centrifugal force will cause the mercury to drop in hole SI! and rise in holes 5!. When a certain speed of governor 44 is reached, the mercury will rise to some elevation such as B in the outer holes 41 and drop to level C in the central hole 66. At some point in the vicinity of this speed and as the speed is incrementally increased by small amounts, the mercury level in the central hole 56 will incrementally drop, and as this occurs the current in the coils of torque motor 56 will be decreased and the butterfly valve will start to close, reaching a full closed position when only a very small portion of the tip of pointed graphite resistor 54 is immersed in the mercury in central hole 50.

To summarize the above description, the operation of governor 44 and electrically-operated butterfly valve 55 is such that a small percentage speed change, such as 5 to 10%, will cause butterfly valve 55 to go from its closed to its open position, or vice versa.

If the design is such that the butterfly valve 55 starts to close when governor 44 is rotating at 500 R. P. M. and is completely closed when governor 44 is rotating at 550 R. P. M., and if it is connected mechanically through a fixed drive to an automobile engine with such a ratio that the car in high gear travels 30 miles an hour when governor 44 is rotating at 500 R. P. M., it is quite obvious that the operation of governor 44 and butterfly valve 55 would maintain the car speed at somewhere between 30 and 33 miles an hour regardless of engine load.

To bring this out further, assume that the car is travelling on the level at 31.5 miles per hour with the throttle about half open. If now a slight upgrade is encountered, the car speed would drop. This would decrease the speed of motor and the level of mercury in hole would rise; butterfly valve would open, and this would result in the car speed being maintained on this upgrade at some speed slightly above 30 miles an hour. If a slight downgrade were encountered, the throttle would close sufficiently to maintain the car speed at a value not exceeding 33 miles per hour unless, of course, the downgrade were steep enough so that a speed of 33 miles an hour would be exceeded even with the butterfly valve 55 closed.

Such an operation would be satisfactory also for certain stationary engines which it is desired to regulate for a substantially constant speed regardless of load; but, of course, it could not as thus far described be used for an application in which it is desired that the speed at which the engine was to regulate must be manually varied.

An automobile is, of course, such an application; so to make the above described system practical, a speed variator is provided, this consisting of the driven and driving wheels 4| and 35 and a variable position fiber disk idler 36 frictionally engaged with the two wheels 35 and 4|.

As above described, this particular governor 44 may be assumed to do all of its regulating between 500 and 550 R. P. M. If it is assumed that it is desired to have the automobile engine operate on a regulated basis between 200 and 4000 R. P. M., it would be necessary to have this variable device installed and so arranged that its ratio might be altered by the drivers foot or hand.

It will be observed that with fiber disk 36 in the position shown, wheel 35 will, as previously described, make about 10 revolutions to one revolution of wheel 4|. With fiber disk 36 in this position, therefore, the engine would be regulated to maintain a speed between 5000 and 5500 R. P. M. as this corresponds to the 500 to 550 R. P. M. of governor H. The above is, of course, based upon assuming that wheel 36 rotates at engine speed. If fiber disk 36 were rotated to the other extreme position as indicated by dotted lines connecting wheels 35 and 4|, then about 200 R. P. M. of the engine would rotate governor 44 at 500 R. P. M. so that under this condition governor 46 would regulate to maintain the engine speed between 200 and 220 R. P. M. regardless of load.

It is obvious therefore that since this speed variator is a stepless device, it may be placed in any position and thus would regulate the engine through a 10% range at any speed between about 200 and 5000 R. P. M.

The position of fiber disk 36 with respect to to fiber disk 36, the other assemblies being left out of this sketch. Forked member 40 carries a socket 61 at its right-hand end in which fits a ball member 68 which is fastened by a bent arm 69 to shaft 10 to which lever 66 is also fastened.

Assuming that the engine is not running, any motion of the foot throttle will rotate shaft 40 through a certain angle and will skew forked member 40 and fiber disk 36 with respect to each other. 'I'his motion in itself would not directly change the ratio of the variable speed assembly but such a change in ratio will almost instantly occur when the engine is running; as, whenever fiber disk 36 is thus skewed, the direction of rotation of wheels 35 and 4| is such that fiber disk 36 will travel on wheels 35 and 4| until the skew has disappeared and a new position is reached corresponding to the particular position in which lever 66 has been placed by the foot throttle. In other words, this speed variator is a self-energizing device in which the operation of the foot throttle causes a misalignment or skewing of fiber disk 36 with respect to fork 40 and the rotation of the device instantly tends to correct the skewing and take the new desired position.

It will thus be observed that this speed variator, combined with the coordinated operation of governor 44 and butterfly valve 55, results in the engine speed being governed within small limits at any speed desired over its entire range as determined by the position of the foot throttle and under all circumstances regardless of load on the engine. A person therefore with this device could drive all day in rolling country at 45 miles an hour by merely keeping his foot in the same position representing 45 miles an hour and the butterfly valve 55 would open and close as required to maintain this speed regardless of whether the car is going up or down or on the level.

The heart of this device is, of course, mercury governor 46 and the heart of the latter is the special characteristics which have been tested and obtained with the specific pointed graphite resistor.

A second part of the invention is the design of the speed variable speed transmission. This speed variator has a number of unique features 10 which I have never observed in any friction drive and by itself is useful for driving small machine tools such as lathes and drill presses. The basic features of this speed variator which distinguish it from other apparently similar friction devices are:

1. The control is self-energizing and to change the ratio the operator does not have to force a friction wheel to slide sideways. This also permits such a speed variator to be adjusted before a machine is started and when the machine starts, it will instantly jump to the preset ratio.

2. A very large ratio is obtainable, it being about 24:1 with this design. Most speed variators do not have a range of more than onethird or one-fourth of this amount; and

3. When fiber disk 36 is in the position shown, which is the maximum slow-down ratio, substantially all of the contacting surface of fiber disk 36 or wheel 35 is operating at the same radius.

In other words, this concave design provides unique advantages in which internal friction represented by different peripheral speeds contacting the width of fiber disk 36 is decreased. The ordinary friction drive does not possess this advantage and becomes worse and worse as the driven fiber wheel approaches the center of the driving disk at right angles to it.

In the foregoing, I have described my invention in connection only with specific illustrative embodiments and specific application thereof. Since many modifications and applications of my invention should now be obvious to those skilled in the art, I prefer to be bound, not by the specific disclosures herein, but only by the appended claims.

I claim:

1. A speed governor comprising a casing of conductive material; a body of conductive liquid in said casing; the upper surface of said conduction liquid being free to rise and fall; a conductive electrode having an end extending continuously into the upper surface of the center of said body liquid; means for rotating said casing to cause the portion of the liquid engaged by said electrode to fall to a degree predetermined by the speed of rotation of the casing; said electrode having substantial electrical resistance; said casing, said liquid and said electrode being placed in series in an electrical circuit; the resistance of said circuit being controlled by the length of electrode immersed in the liquid.

2. A speed governor comprising a casing of conductive material; a body of conductive liquid in said casing; the upper surface of said conduction liquid being free to rise and fall; a conductive electrode having an end extending continuously into the upper surface of the center of said body liquid; means for rotating said casing to cause the portion of the liquid engaged bysaid electrode to fall to a degree predetermined by the speed of rotation of the casing; said electrode having substantial electrical resistance; said casing, said liquid and said electrode being placed in series in an electrical circuit; the resistance of said circuit being controlled by the length of electrode immersed in the liquid and means for preventing said liquid from spinning with respect to said casing.

3. A speed governor comprising a casing of conductive material; a body of conductive liquid in said casing; the upper surface of said conductive liquid being free to rise and and fall; a conductive electrode having an end extending continuously into the central portion of the upper surface of said liquid; means for rotating said casing to cause the portion of the liquid engaged by said electrode to fall to a degree predetermined by the speed of rotation of the casing; said electrode having substantial electrical resistance; said casing, said liquid and said electrode being placed in series in an electrical circuit; the resistance of said circuit being controlled by the length of electrode immersed in the liquid.

4. A speed governor comprising a casing of conductive material; a body of conductive liquid in said casing; the upper surface of said conductive liquid being free to rise and fall; a conductive electrode having an end extending continuously into the central portion of the upper surface of said liquid; means for rotating said casing to cause the portion of the liquid engaged by said electrode-to fall to a degree predetermined by the speed of rotation of the casing; said electrode having substantial electrical resistance; said casing, said liquid and said electrode being placed in series in an electrical circuit; the resistance of said circuit being controlled by the length of electrode immersed in the liquid and means for controlling the extent of immersion of said electrode in said liquid; said means also controlling the speed of rotation of the casing.

5. A speed governor comprising a casing of conductive material; a body of conductive liquid in said casing; the upper surface of said conductive liquid being free to rise and fall; a conductive electrode having an end extending continuously into the central portion of the upper surface of said liquid; means for rotating said casing to cause the portion of the liquid engaged by said electrode to fall to a degree predetermined by the speed of rotation of the casing; said electrode having substantial electrical resistance; said casing, said liquid and said electrode being placed in series in an electrical circuit; the resistance of said circuit being controlled by the length of electrode immersed in the liquid; said means for rotating the casing including a motor; said motor being controlled by said speed governor; and means for varying the speed of said motor; said last mentioned means correspondingly varying the extent of immersion of said electrode in said liquid.

6. A speed governor comprising a casing of conductive material; a body of conductive liquid in said casing; the upper surface of said conduction liquid being free to rise and fall; a conductive electrode having an end extending continuously into the upper surface of the center of said body liquid; means for rotating said casing to cause the portion of the liquid engaged by said electrode to fall to a degree predetermined by the speed of rotation of the casing; said electrode having substantial electrical resistance; said casing, said liquid and said electrode being placed in series in an electrical circuit; the resistance of said circuit being controlled by the length of electrode immersed in liquid and means for preventing said liquid from spinning with respect to said casing; said means comprising a vertical annular wall in said casing dividing said casing into a central chamber and an annular concentric outer chamber.

'7. A speed governor comprising a casing of conductive material; a body of conductive liquid in said casing; the upper surface of said conduction liquid being free to rise and fall; a conductive electrode having an end extending continuously into the upper surface of the center of said body liquid; means for rotating said casing to cause the portion of the liquid engaged by said electrode to fall to a degree predetermined by the speed of rotation of the casing; said electrode having substantial electrical resistance; said casing, said liquid and said electrode being placed in series in an electrical circuit; the resistance of said circuit being controlled by the length of electrode immersed in liquid and means for preventing said liquid from spinning with respect to said casing; said means comprising a wall in said casing defining a central chamber; and at least a pair of side chambers;

and connections between the upper and lower ends of each side chamber and the central cham- 8. A speed governor comprising a casing of conductive material; a body of conductive liquid in said casing; the upper surface of said conduction liquid being free to rise and fall; a conductive electrode having an end extending continuously into the upper surface of the center of said body liquid; means for rotating said casing to cause the portion of the liquid engaged by said electrode to fall to a degree predetermined by the speed of rotation of the casing; said electrode having substantial electrical resistance; said casing, said liquid and said electrode being placed in series in an electrical circuit; the resistance of said circuit being controlled by the length of electrode immersed in the liquid and means for preventing said liquid from spinning with respect to said casing; said means comprising a wall in said casing defining a central chamber; and at least a pair of side chambers; and connections between the upper and lower ends of each side chamber and the central chamber; said side chambers being tilted with respect to said central chamber.

9. A speed governor comprising a casing of conductive material; a body of conductive liquid in said casing; the upper surface of said conduction liquid being free to rise and fall; a conductive electrode having an end extending continuously into the upper surface of the center of said body liquid; means for rotating said casing to cause the portion of the liquid engaged by said electrode to fall to a degree predetermined by the speed of rotation of the casing; said electrode having substantial electrical resistance; said casing, said liquid and said electrode being placed in series in an electrical circuit; the resistance of said circuit being controlled by the length of electrode immersed in liquid and means for preventing said liquid from spinning with respect to said casing; said means comprising a wall in said casing defining a central chamber; and at least a pair of side chambers; and connections between the upper and lower ends of each side chamber and the central chamber; said side chambers being tilted with their upper ends closer to the central chamber than their lower ends.

10. A speed governor comprising a casing of conductive material; a body of conductive liquid in said casing; the upper surface of said conduction liquid being free to rise and fall; a conductive electrode having an end extending continuously into the upper surface of the center of said body liquid; means for rotating said casing to cause the portion of the liquid engaged by said electrode to fall to a degree predetermined by the speed of rotation of the casing; said electrode having substantial electrical resistance; said casing, said liquid and said electrode being placed in series in an electrical circuit; the resistance of said circuit being controlled by the length of electrode immersed in liquid and means for preventing said liquid from spinning with respect to said casing; said means comprising a wall in said casing defining a central chamber; and at least a pair of side chambers; and connections between the upper and lower ends of each side chamber and the central chamber; said side chambers being tilted with their lower ends closer to the central chamber than their upper ends.

11. A speed governor comprising a casing of conductive material; a body of conductive liquid in said casing; the upper surface of said conduction liquid being free to rise and fall; a conductive electrode having an end extending continuously into the upper surface of the center of said body liquid; means for rotating said casing to cause the portion of the liquid engaged by said electrode to fall to a degree predetermined by the speed of rotation of the casing; said electrode having substantial electrical resistance; said casing, said liquid and said electrode being placed in series in an electrical circuit; the resistance of said circuit being controlled by the length of electrode immersed in the liquid and means for preventing said liquid from spinning with respect to said casing; said means comprising a wall in said casing defining a central chamber; and at least a pair of side chambers; and connections between the upper and lower ends of each side chamber and the central chamber; said electrode being immersed in the surfa e of the liquid in the central chamber.

12. A speed governor comprising a casing of conductive material; a body of conductive liquid in said casing; the upper surface 01' said conductive liquid being free to rise and fall; a conductive electrode having an end extending continuously into the central portion of the upper surface of the center of said body liquid; means for rotating said casing to cause the portion of the liquid engaged by said electrode to fall to a degree predetermined by the speed of rotation of the casing; said electrode having substantial electrical resistance; said casing, said liquid and said electrode being placed in series in an elecl4 trical circuit; the resistance of said circuit being controlled by the length of electrode immersed in the liquid; said means for rotating the casing including a motor; said motor being controlled by said speed governor; a throttle for varying the speed of said motor; said throttle correspondingly varying the extent of immersion of said-electrode in said liquid.

13. A speed governor for an internal combustion engine having a fuel feed line and a valve in said fuel feed line for controlling the flow of fluid therein, said speed. governor comprising a casing of conduction material; a conductive liquid in said casing; the upper surface of said con- .ductive liquid being free to rise and fall; a conductive electrode having an end extending continuously into the upper surface of said liquid; means for rotating said casing to cause the portion of the liquid engaged by said electrode to fall to a degree predetermined by the speed of rotation of the casing; said electrode having sub stantial electrical resistance; said casing, said liquid and said electrode being placed in series in an electrical circuit; the resistance of said circuit being controlled by the length of electrode immersed in the liquid; and electrically operated control means for said valve; said last mentioned electrically operated valve control means being in electrical series with said electrical circuit.

DONALD I. BOHN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 35,589 Dulon June 17, 1862 196,846 Werton -1 Nov. 6, 1877 476,311 Replogle June 7, 1892 1,036,596 Fisher Aug. 27, 1912 1,734,802 French Nov. 5, 1929 1,883,565 Christiansen Oct. 18, 1932 2,164,991 Ingres July 4, 1939 2,203,477 Wahlberg June 4, 1940 2,210,082 Johnson Aug. 6, 1940 2,334,720 Marsh Nov. 23, 1943 2,359,927 Melas Oct. 10, 1944 FOREIGN PATENTS Number Country Date 35,157 Switzerland Dec. 5, 1905 

